In general, detergent compositions intended for washing clothes are expected to provide copious suds during the washing cycle, although in recent years there has been a growing interest in avoiding excessive sudsing even at this stage. It is also important that the rinse water should not carry appreciable amounts of suds, especially in the second or later rinses, since such suds interfere with proper drainage of the rinse water from the wash tub or machine and may give an erroneous impression that rinsing has been inadequate. Soap products have generally been good in this respect, with the exception that in very soft water water hardness in the rinse effectively kills any suds. Anionic synthetic detergent products tend to provide very copious suds, sometimes excessive, in the wash and produce excessive suds in the rinse. In these products this latter fault can be countered by using known additives in the compositions, such as long chain soaps or fatty acids, silicone compounds and so forth. Usually these additives depress the suds in the washing step, but often this is an advantage or at least acceptable. Up to the present, most anionic detergent compositions have included considerable proportions of phosphate detergency builders.
Detergent compositions based upon nonionic detergents, or zwitterionic detergents alone and particularly mixtures thereof, or with anionic detergents can achieve improved cleaning compared with anionic detergents alone, especially when little or no phosphate builder is present. These compositions generally can provide adequate suds in the wash, but they tend to cause a severe problem of stable suds in the rinse. The usual suds depressants, suitable for use with anionic detergents, have proved unsuitable for correcting this fault. They fail for various reasons, for instance, they may be effective in the rinse at levels at which they also unduly depress the suds in the wash or at which they impair the cleaning performance or other properties of the product.
It is thus an object of the present invention to provide a detergent composition having depressed sudsing in the rinse.
It is a further object of this invention to provide suds control in the rinse without undue suds depression in the wash.
It has been found that it is possible to reduce the suds in the rinse arising from the use of nonionic, zwitterionic, or anionic synthetic detergents without unduly reducing the sudsing during the washing step. This is particularly valuable for detergent compositions based on nonionic or nonionic and zwitterionic mixed surfactants. Furthermore, the compositions of the invention can be selected so that a degree of suds suppression in the wash can be achieved in cases where such is desired.
Temperatures are in Centigrade and percentages and ratios are by weight unless otherwise indicated.